This invention, in one of its aspects (the preferred aspect), relates to a medical-assistant system and method utilizing digital computer processing for interpreting a specific subject's electrocardiographic (ECG) waveforms. In particular, and with regard to this aspect, it relates to such a system and method which, after performing a computer-implemented interpretation of input ECG data, ultimately creates a pictorial, representational output display of the heart marked, inter alia, with distinctive visual elements (markers) that show, with a very high degree of configurational and other accuracy, the natures, presences, sizes, locations, and other aspects, of certain selected heart conditions. These conditions, also referred to herein as features (or regions), include (without limitations) any one (or more) of the following: (a) myocardial infarcts (old, acute and subacute); (b) ventricular mass; (c) all forms of hypertrophy; (d) localized ischemia; (e) ectopic foci; and (f) any other heart condition of interest (such as activation wavefront information) which is detectable in ECG data. The resultant, desired pictorial output display (static, and/or with motion) can be presented (1) on a screen such as a computer monitor or a projection screen, (2) as a spatially floating real image, (3) on a printed sheet of material, or (4) in any other suitable manner.
Another aspect of the invention involves a medical-assistant system and method including an input zone structure adapted to receive an already prepared computer interpretation signal containing heart-condition information like that just mentioned. This input zone structure is coupled to what is called herein a pictorial display subsystem which uses the already prepared signal to produce the desired pictorial output display.
In operation, the system of the invention in its preferred aspect is furnished with an input collection (or stream) of subject-specific ECG-related data. This data may come in the form of ECG wave data derived directly and "currently" from a particular subject, or in the form of ECG data earlier gathered from a selected subject and made available from a suitable pre-collection database, or in any other appropriate fashion. The specific ECG data provided as an input to the system may either be substantially pure and unprocessed en route to the system, or it may be in a form which has, in some way, been pre-processed in accordance with various selectable and conventionally understandable ECG-wave processing techniques. For example, arriving input ECG information may have been preprocessed through a temporal filter to remove certain electrical interference signals; it may have been preprocessed to determine interval measurements of P, ORS, and T wave offsets; it may have been preprocessed to determine certain wave amplitudes; etc. Additionally, this data may include components that result from the presence and operation of a pacemaker.
In the preferred form of the invention, the proposed system includes: (a) a first data input structure adapted to receive, from a selected subject, ECG-related data in one of the forms just mentioned above; (b) a second data input structure adapted to receive, selectively, one or two categories of physiological/anatomical data, as well as a collection of predetermined rules (also referred to as rules and criteria, as rule sets and criteria sets, and as score cards) designed to be used in the interpretation process; and (c) a digital computer (data-processing structure) which conducts the intended interpretation. The computer just mentioned is also referred to herein as being a part of an interpretation system, and it can take any one of a number of different specific forms, including a form wherein its structure is distributed in and throughout the system. The predetermined rules and criteria are also referred to herein as being expressions of selected interpretation protocols. The two categories of physiological/anatomical data include (1) general, non-subject-specific, heart-related physiological reference data preacquired from a large population of people and appropriately organized in accordance with typical heart-normalcy or heart-abnormalcy and other factors (identified more specifically below), and (2) a collection of subject-specific physiological/anatomical data (including medical history data), such as (but not limited to) subject height, weight, sex, race, torso configuration, prescription drug-use history, heart size, heart location and heart orientation. Such "heart" information is typically inferred, at least in part, from external, anatomic measurements. The input ECG-related data is also called a first collection of data, and the other data mentioned is also called, collectively, a second collection of data. The mentioned subject-specific collection of data can be input the system at the time of inputting a particular subject's ECG-related data, or it can be made appropriately available from, for example, a pre-created subject data base.
Also taken into account in the preferred practice of the invention (though not in all approaches toward employment of the invention) is information (such as presence, and level of severity (LV mass)) relating to all forms of hypertrophy, such as left and right ventricular hypertrophy. In the description which is given below of a preferred form of the invention, that form is presented herein, just for illustration purposes, in the context of receiving and employing information regarding left ventricular hypertrophy (LVH) and LV mass.
Preferably included in the organized, non-subject-specific, general-population reference collection of such data is information regarding gender, age, race, height, weight, body build, transverse chest measurements, and related information concerning expected major variances attributable to differences in typical male and female torso anatomy. Also preferably included in such a library of general-population data, is additional information describing typical normal conduction, ventricular and other hypertrophies, typical anterior, inferior and posterior infarcts of all sizes, and regional sub-endocardial, mural and transmural injury-ischemia. Further, this collection of general-population data preferably covers a range of subjects which would include, by physiological and anatomical characteristics, each specific singular type of subject whose ECG data might be expected to be interpreted by the system and method of this invention.
As will be more fully described below, according to the preferred manner of practicing the present invention, the implemented interpretation process involves the use of both subject-specific physiological/anatomical data, and in relation thereto, selected data contained in the general-population physiological/anatomical database. This selected data is that which is most closely associated with a subject whose physical characteristics substantially match (or are as close as possible to) those of the specific subject whose ECG data is being examined.
As will be discussed below, the present invention also embraces modifications which relate, inter alia, to (1) the use or non-use of inference interpretation following rules application, (2) to the use or non-use of one or both categories of the above-mentioned physiological/anatomical data, and (3) to the use or non-use of hypertrophy information. Not all of these recognized modifications are specifically represented in the drawings presented herein. Rather, some of them are introduced and discussed only in text which describes them in relation to easily pictured variations of particular drawing figures which are specifically presented herein.
The central preferred heart-related method implemented by the system of the present invention can be described as including the steps of: (a) accessing, acquiring or receiving an input collection of subject-specific ECG-related data sourced ultimately from a specific living subject; (b) computer-processing (analyzing) that data to develop an interpretation (interpretation analysis) which relates to detection and characterization of certain selected heart conditions; and (c) generating, or effecting, a pictorial, representational output display of the subject's heart (also called herein a heart-representational visual display), with that display including, inter alia, visual markers specifically and inferentially associated with the found and characterized selected heart condition or conditions. This pictorial output display is created in response to what is referred to herein as a visual-pictorial-display-enabling interpretation output signal--a final output signal which results from the mentioned computer processing.
Generally speaking, the application of rules and criteria to ECG data for the purposes of interpreting pathological conditions is well known in the art. It is also known that physiological conditions such as race, age and sex of a subject are important to take into account when applying the rules and criteria. However, significantly lacking in the prior art is knowledge relating to the use of rules and criteria in the presence of ECG "confounding" conditions, such as left ventricular hypertrophy, right bundle branch block, left ventricular fascicular block, and intraventricular conduction block. These and other confounding conditions, such as left bundle branch block and pacing due to a pacemaker, currently appear, according to conventional thinking, to prevent the use of rules and criteria in a computerized ECG interpretative system.
With our new system and method, we offer a way through and beyond this dilemma.
The method and system proposed by this invention can be used either in a current-time, or in a later-time (time-displaced or time-sequential), kind of interpretive activity. They can derive ECG input information in a host of different ways (discussed more fully below). Utilizing direct, rule-based computer analysis of ECG wave data, including the applications of selected rules and criteria for interpretation, and the employment of selected inferences, they can quickly produce a highly informative visual, pictorial output display of the type generally mentioned above. In the output display, they can offer different kinds of pictorial points of view. Further, they afford the opportunity to make rapid, visual, time-separated comparisons which can clearly show changes in a selected heart condition.
In addition to what has been stated above about our new system and methodology, this system and methodology is capable of furnishing, in pictorial display form, (a) a predictive output display which forecasts changes in heart condition that might be expected at different later points in time, and (b) a cine-loop type motion display which shows how a detected condition affects heart pulsation. For example, it is possible to use the system and method of this invention in a serial-comparison mode of operation, wherein the kinds of activities that are predictive precursors to the onset of an acute myocardial infarct can be detected, pictured and relied upon to initiate preemptive medical intervention. Describing generally how such predictive behavior can take place using the present invention, the following representative actions are illustrative: (a) on the basis of one ECG interpretation procedure, producing a pictorial display of the heart, marked with a selected heart condition existing at time T.sub.1 ; (b) on the basis of another, later ECG interpretation procedure, producing another pictorial display of the heart, marked with a related selected heart condition existing at time T.sub.2 ; (c) applying an appropriate future-condition-predictive knowledge database associated with the differences existing in the displays of conditions at times T.sub.1 and T.sub.2 ; and (d) offering a predictive interpretation as an outcome of action (c).
Another unique capability of the system and method of this invention is that it can be employed, on the basis of a given interpretation which it performs, to produce a display (relative to that interpretation) that pictures electrical activation wavefronts associated with the heart condition found in the interpretation. Such wavefronts can be presented in various visual ways, such as in distinctive bands of color, which represent time and spatial displacement in the heart.
Augmenting and reinforcing what was just said above about the output display, this display can be presented in the form either of a static or of a motion display. It can be shown in the form of a floating, real-image display. And, it can be furnished in a manner which permits elaborate, real-time user manipulation (for example, selective rotation). As was stated earlier, of course, other manners of display are possible. For example a resulting pictorial output display could be transmitted to a remote location, as, for example, by transmission over the Internet.
If desired, the final interpretation output information can further include (along with a pictorial display) any one or more of: (a) a written report; (b) an appropriate alarm signal (as, for example, in a typical patient-monitoring mode of activity); (c) an action control signal, such as a signal which causes the automatic administering of a medication; and (d) other things.
While various different representational visual display formats can be employed to suit different applications, one format which we believe will be considered to be very effective in many instances, and which is specifically illustrated herein, is the screen-borne (or printed) format of a map-like Mercator projection of the epicardial (outer) surface of the left ventricle (accompanied, if desired, by a single-side view of the right ventricle). Specifically what is shown in one of the drawing figures herein is a view which includes, in addition to the just-mentioned, single-side right ventricle view, such a Mercator projection, wherein the left ventricle is displayed in four quadrants as described by Ideker, each quadrant being divided into basal, middle and apical segments. For ease of identification and orientation, these segments are conventionally numbered 1-12, inclusive. In this generally representational display, and specifically in the left-ventricle part of the display, there is an image of a single, moderate-size infarct which extends over two quadrants and several segments of the left-ventricle. The displayed infarct takes the form of a patterned, or color-highlighted, shape. This shape generally expresses visually the location, size, configuration and disposition of the infarct. Such patterning or color-highlighting, which can take any one (or more) of a number different forms, is very useful in identifying and detailing subtle differentiating characteristics that are present within a detected condition, such as within an infarct. In the particular representative displays (and there are several) presented herein, such patterning/highlighting is employed to reveal infarct density information.
Representative displays of other conditions, such as displays regarding ectopic foci and ischemia, are not specifically pictured in the drawings. Rather, these other kinds of displays are described in text which relates them to the particular infarct displays that are shown in the drawings.
Other advantages which are offered by the present invention will become more fully apparent as the system and method descriptions which now follow are read in conjunction with the accompanying drawings.